如何在 .NET Core 中发送和接收包含 multipart/form-data 的文件？

Question

使用 .NET Core 3.1，我有以下构建 HTTP POST 包含 multipart/form-data 正文的 Http 客户端：

public async Task SendRequest(string randomString, IFormFileCollection files) 
{
    var form = new MultipartFormDataContent();
    
    form.Add(new StringContent(randomString), "randomString");
    
    foreach (var file in files)
    {
        var stream = new MemoryStream();
        await file.CopyToAsync(stream, cancellationToken);
        form.Add(new StreamContent(stream), "files");
    }

    using var request = new HttpRequestMessage(HttpMethod.Post, $"api/endpoint")
    {
        Content = form
    };

    await _httpClient.SendAsync(request);
}

接收控制器如下所示：

[Consumes("multipart/form-data")]
[HttpPost]
public async Task ReceiveForm([FromForm] RequestModel request)
{
    //Do stuff
}

RequestModel 看起来像这样：

public class RequestModel 
{
    [JsonPropertyName("randomString")]
    public string RandomString { get; set; }

    [JsonPropertyName("files")]
    public IFormFileCollection Files { get; set; }
}

我看到的问题是 requestModel.RandomString 被填充，但 requestModel.Files 没有填充 - 它为空。我做错了什么？

Answer 1

感谢示例中的完美代码！

您应该将两个参数（名称和文件名）设置为文件 - form.Add(new StreamContent(stream), "files", "files");

方法说明：

Parameters:
content: The HTTP content to add to the collection.
name: The name for the HTTP content to add.
fileName: The file name for the HTTP content to add to the collection.

这是我的例子：

var fileName = "files";
var byteArrayContent = new ByteArrayContent(fileBytes1);
form.Add(byteArrayContent, fileName, fileName);

var stream = new MemoryStream(fileBytes2);
form.Add(new StreamContent(stream), fileName, fileName);

结果：

如何在 .NET Core 中发送和接收包含 multipart/form-data 的文件？

How to send and receive multipart/form-data containing files in .NET Core?

http

.net-core

asp.net-core

asp.net-core-webapi